The synthesis of 1, 3-diarylimidazolidin-2-ylidene (NHC) precursor, 1, 3-bis (2, 4, 6- trimethylphenyl) imidazolinium chloride,(3b) has been extended to the electronically and sterically modified NHC precursors 3a (X= H), 3c (X= Br) and 3e (X= Cl) in order to investigate the electronic effect of a p-substituent (X) on cross-coupling catalysts. Complexes of the type PdCl2 (NHC) 2 (5), PdCl2 (NHC)(PPh3)(6) and [RhCl (NHC)(cod)](7) were ...